It is well known to drive an electrical generator with a prime mover attached to the rotor shaft of the generator. Typically, the generator electrical output is provided responsive to the excitation of a field coil in the generator; the field coil itself and the separate field excitation electronics are both costly and undesirable. Further, use of excited field coils will often cause the generator to operate at reduced efficiency. This is normally undesirable, and is especially so when the combination of prime mover and electrical generator is contained in an electric vehicle, where the wheels are driven by a motor receiving power provided either directly or indirectly from the generator; maximization of efficiency will not only improve fuel consumption, but may also result in minimization of pollution and other undesirable characteristics.
It is therefore desirable to provide a permanent magnet generator, devoid of field coil and field excitation means, which is driven, with maximized efficiency, directly by the prime-mover.